This quotation alludes to one of the most fundamental problems in philosophy. Finding out the real nature of things, understanding the fundamentals of our world has always been one of the greatest desires of many philosophers; Plato, Descartes, Spinoza, Kant, to name only a few. This essay deals with the scope of our knowledge. It will concentrate on the limitations of our perception and discuss the statement above.

Usually, we do not think intensively about reality. People get up in the morning, they go to work and come back in the evening. Some of them have a family. They play with their kids, talk to their wifes and go fishing on week-end. Why worry about reality? What is the problem here? Don't I already know how "things really are""

This attitude, known as Naïve Realism, is quite hard to maintain. Consider for example our mind. Is it...